This invention relates to skate retarders for railway cars and, more particularly, to a releasable skate retarder including a wear adjustment mechanism.
Fixed spring-loaded retarders are commonly employed in railway classification yards. The basic function of a fixed, spring-loaded retarder is to offer a preset resistance to all railway cars that are directed into the retarder. This is provided by devices that are installed in a section of railway track to retard or arrest the rolling movement of railway cars by pressing a friction rail against the wheels of the railway cars so that the railway cars are braked by friction. One type of retarder, commonly referred to as a skate retarder, is used primarily for stopping the first railway car directed into a classification track, to allow other railway cars to be coupled to the first railway car. When several railway cars have been coupled together, the string of railway cars is pulled through the retarder.
One shortcoming of spring-loaded retarders is that the preset resistance cannot be varied without time consuming readjustment of several fastenings that hold the retarder in place. When a string of railway cars is being pulled through the retarder by a locomotive, considerable squeal noise is produced. Moreover, the high resistance to motion afforded by the retarder to all of the railway cars in the string results in considerable wear and tear on the locomotive needed to pull the string of railway cars through the retarder. Also, fuel costs are increased due to the energy required to pull a string of railway cars through the retarder. A further limitation is that the friction rails are subject to wear and must be replaced periodically as they wear. Moreover, pulling a string of railway cars through the retarder while the wheels of the railway cars are wedged between the riding rails and the friction rails can result in fatigue on the springs.
Various approaches have been proposed for reducing wear of friction rails in railway car retarders. By way of example, in U.S. Pat. No. 5,388,525, issued on Feb. 14, 1995, which was issued to W. Andrew Bodkin, there is disclosed a mechanism which allows release of the friction rails, allowing the railway cars to be moved through the retarder with reduced wear on the friction rails. The compression springs are positioned in pairs between brackets and the friction rails. A separate hydraulic release is provided for each pair of springs. The brackets are secured against dislocation from the spring force by cap screws which are received in tapped holes in the gauge plate and by clamping devices including hooked rod members and jaw members. By way of providing compensation for wear, replaceable wear plates are bolted to the friction rails. The wear plates can be replaced or reoriented when they become worn. However, this requires loosening the bolts for each bracket and adjusting the hooks to change the wear plates. This is a time consuming task considering the large number of spring pairs that employed. For example, replacement of the wear plates can take two or more hours, and the cost for such maintenance can be considerable. Moreover, during this results in considerable down time for the classification yard.
The present invention provides a releasable retarder for railway cars. The retarder includes a first and second shoe beams, which support replaceable shoes in parallel, spaced relation with first and second running rails. A plurality of spring packs includes springs which bias the shoe beams toward the running rails, trapping wheels of a railway car entering the retarder between the shoes carried by the shoe beams and the running rails, and applying a frictional force to the railway car wheels for stopping the railway car and retaining the railway car in the retarder. An operating mechanism moves the shoe beams between a home position in which the shoes are positioned to engage the railway car wheels, and a release position in which the spring force is released, allowing the railway car to move freely through the retarder. The operating mechanism includes a plurality of rams and a common operating member which couples the rams to the spring packs, for causing the springs to be compressed, drawing the shoe beams inwardly away from the running rails to the release position. In one embodiment, the common operating member is coupled to the spring packs through a plurality of lever systems.
In accordance with another aspect of the invention, the retarder provides for rapid and easy adjustment of the gap between the shoes and the running rails for compensating for wear of the shoes. In one embodiment, the rams are bidirectional devices, allowing the retarder to function also in a service mode in which the operating mechanism moves the shoe beams outwardly, allowing the insertion of shims. The presence of the shims causes the shoes to be repositioned closer to the running rails, compensating for wear on the shoes.